U.S. patent application number 13/277659 was filed with the patent office on 2013-01-03 for holographic recording medium.
This patent application is currently assigned to SABIC INNOVATIVE PLASTICS IP B.V.. Invention is credited to Mark A. Cheverton, Gary Davis, Sumeet Jain, Pradeep Nadkarni, Shantaram Narayan Naik, Kiran Arunkumar Puthamane, Michael T. Takemori, Vinodkumar Vasudevan.
Application Number | 20130004887 13/277659 |
Document ID | / |
Family ID | 46548828 |
Filed Date | 2013-01-03 |
United States Patent
Application |
20130004887 |
Kind Code |
A1 |
Naik; Shantaram Narayan ; et
al. |
January 3, 2013 |
HOLOGRAPHIC RECORDING MEDIUM
Abstract
Disclosed herein are novel nitrone compounds, holographic
recording media that include the nitrone compound(s) and a polymer
binder, a method of manufacturing a holographic recording medium
where the nitrone compound, as a photochromic dye, is mixed with a
polymer binder to form a holographic composition and molding the
holographic composition into holographic data recording medium.
Disclosed herein too is a method for recording a hologram by
exposing the holographic recording medium to mutually coherent
signal and reference light sources at a wavelength that causes a
change in the chemical structure of the nitrone compound.
Inventors: |
Naik; Shantaram Narayan;
(Bangalore, IN) ; Takemori; Michael T.; (Rexford,
NY) ; Jain; Sumeet; (Schenectady, NY) ;
Nadkarni; Pradeep; (Bangalore, IN) ; Cheverton; Mark
A.; (Mechanicville, NY) ; Puthamane; Kiran
Arunkumar; (South Kodagu, IN) ; Vasudevan;
Vinodkumar; (Kerala, IN) ; Davis; Gary;
(Albany, NY) |
Assignee: |
SABIC INNOVATIVE PLASTICS IP
B.V.
Bergen op Zoom
NL
|
Family ID: |
46548828 |
Appl. No.: |
13/277659 |
Filed: |
October 20, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13171640 |
Jun 29, 2011 |
|
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13277659 |
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Current U.S.
Class: |
430/2 ;
560/44 |
Current CPC
Class: |
C07C 291/02 20130101;
G11B 7/24044 20130101; G03F 7/001 20130101; G03H 1/0248 20130101;
G03H 2260/52 20130101; G11B 7/245 20130101; G03H 1/0236 20130101;
G11B 2007/240025 20130101 |
Class at
Publication: |
430/2 ;
560/44 |
International
Class: |
G03F 7/032 20060101
G03F007/032; C07C 229/52 20060101 C07C229/52; G03H 1/04 20060101
G03H001/04 |
Claims
1. A holographic recording composition comprising a polymer binder
and a nitrone compound according to the formula: ##STR00034##
wherein R.sub.1 and R.sub.2 are each independently C.sub.1-C.sub.10
alkyl.
2. The holographic recording composition of claim 1, wherein
R.sub.1 and R.sub.2 are each independently C.sub.1-C.sub.8
alkyl.
3. The holographic recording composition of claim 1, wherein
R.sub.1 and R.sub.2 are each independently C.sub.1-C.sub.6
alkyl.
4. The holographic recording composition of claim 1, wherein
R.sub.1 and R.sub.2 are each independently C.sub.1-C.sub.4
alkyl.
5. The holographic recording composition of claim 1, wherein
R.sub.1 and R.sub.2 are each independently methyl or ethyl.
6. The holographic recording composition of claim 1, wherein
R.sub.1 is methyl and R.sub.2 is ethyl.
7. The holographic recording composition of claim 1, wherein the
polymer binder is a thermoplastic polymer, a thermoset polymer, or
a coating.
8. The holographic recording composition of claim 1, wherein the
polymer binder is a polycarbonate, a polyestercarbonate, or a
mixture thereof.
9. The holographic recording composition of claim 1, wherein the
polymer binder has a glass transition temperature of at least
120.degree. C.
10. A compound according to the formula: ##STR00035## wherein
R.sub.1 and R.sub.2 are each independently C.sub.1-C.sub.10
alkyl.
11. The compound of claim 10, wherein R.sub.1 and R.sub.2 are each
independently C.sub.1-C.sub.8 alkyl.
12. The compound of claim 10, wherein R.sub.1 and R.sub.2 are each
independently C.sub.1-C.sub.6 alkyl.
13. The compound of claim 10, wherein R.sub.1 and R.sub.2 are each
independently C.sub.1-C.sub.4 alkyl.
14. The compound of claim 10, wherein R.sub.1 and R.sub.2 are each
independently methyl or ethyl.
15. The compound of claim 10, wherein R.sub.1 is methyl and R.sub.2
is ethyl.
16. A composition comprising the compound of claim 10 and a
polymer.
17. The composition of claim 16, wherein the polymer is a polymer
binder having said compound dispersed therein.
18. A method of manufacturing a holographic recording medium,
comprising: mixing a compound according to claim 10 with a molten
thermoplastic polymer binder to form a mixture, and forming the
mixture into a holographic recording medium.
19. The method according to claim 15, wherein the molten
thermoplastic polymer binder is at a temperature of at least
120.degree. C.
20. A method of recording a volume hologram, comprising exposing a
holographic recording medium comprising the composition of claim 1
to mutually coherent signal and reference light sources at a
wavelength that causes a change in the chemical structure of the
compound of formula (I).
21. The method of claim 19, wherein R.sub.1 and R.sub.2 are each
independently C.sub.1-C.sub.6 alkyl.
22. The method of claim 19, wherein R.sub.1 and R.sub.2 are each
independently methyl or ethyl.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part application of
U.S. application Ser. No. 13/171,640 filed on Jun. 29, 2011, the
disclosure of which incorporated by reference in its entirety.
BACKGROUND
[0002] The present disclosure relates to media for recording and
storing holograms, and more specifically to holographic recording
media that include nitrone compounds useful as photoreactive active
dyes.
[0003] Holograms are typically formed by interference fringes in a
holographic recording medium that diffract light in a pattern to
create a readable or viewable hologram. A variety of techniques
have been used to create different types of holograms. Volume
holograms are an increasingly popular mechanism for the
authentication of genuine articles, whether it is for security
purposes or for brand protection. Volume holograms can also be used
for other purposes, such as data storage, or for decorative,
illustrative, or artistic purposes. The use of volume holograms for
authentication purposes is driven primarily by the relative
difficulty with which they can be duplicated. Volume holograms are
created by interfering two coherent beams of light to create an
interference pattern and storing that pattern in a holographic
recording medium. Information or imagery can be stored in a
hologram by imparting the data or image to one of the two coherent
beams prior to their interference. The hologram can be read out by
illuminating it with a beam of light matching the geometry and
wavelength of either of the two original beams used to create the
hologram and any data or images stored in the hologram will be
displayed. As a result of the complex methods required to record
holograms, their use for authentication can be seen on articles
such as credit cards, software, passports, clothing, and the
like.
[0004] Early holographic recording media employed inorganic
photorefractive crystals, such as doped or undoped lithium niobate
(LiNbO.sub.3), in which incident light creates refractive index
changes. These index changes are due to the photo-induced creation
and subsequent trapping of electrons leading to an induced internal
electric field that ultimately modifies the index through a linear
electro-optic effect. However, LiNbO.sub.3 is expensive, exhibits
relatively poor efficiency, fades over time, and requires thick
crystals to observe any significant index changes.
[0005] More recent work has led to the development of polymers that
can sustain larger refractive index changes owing to optically
induced polymerization processes. These materials, which are
referred to as photopolymers, have significantly improved optical
sensitivity and efficiency relative to LiNbO.sub.3 and its
variants. Photopolymer holographic recording media (as disclosed in
e.g., U.S. Pat. Nos. 7,824,822 B2, 7,704,643 B2, 4,996,120 A,
5,013,632 A). "Single-chemistry" photopolymer systems have been
employed, wherein the media comprise a homogeneous mixture of at
least one photoactive polymerizable liquid monomer or oligomer, an
initiator, an inert polymeric filler, and optionally a sensitizer.
Since it initially has a large fraction of the mixture in monomeric
or oligomeric form, the medium can have a gel-like consistency that
necessitates an ultraviolet (UV) curing step to provide form and
stability. Unfortunately, the UV curing step can consume a large
portion of the photoactive monomer or oligomer, leaving
significantly less photoactive monomer or oligomer available for
data storage. Furthermore, even under highly controlled curing
conditions, the UV curing step can often result in variable degrees
of polymerization and, consequently, poor uniformity among media
samples.
[0006] Other types of media and recording techniques have also been
used to generate volume holograms. For example, dichromated
gelatin, liquid crystal materials, photographic emulsions, and
others as disclosed in P. Hariharan, Optical
Holography--Principles, techniques, and applications 2.sup.nd ed.,
Cambridge University Press, 1996, can all be used to generate
volume holograms.
[0007] Another type of holographic recording medium utilizes a
photoreactive dye dispersed in a polymer binder. This approach
offers a number of advantages. Unlike many other volume holographic
recording media, photoreactive dye-based media can be used with a
variety of different types of polymer binders such as
thermoplastics that can provide a number of beneficial physical
properties specific to particular class(es) of thermoplastics
(e.g., polycarbonates), such as toughness, optical clarity, scratch
resistance, strength, flexibility, and the like, as well as ease of
fabricating holographic articles using conventional thermoplastic
fabrication techniques. Different classes of thermoplastics have
different combinations of advantages and disadvantages, which can
be leveraged for the desired final application.
[0008] Photoreactive dyes are compounds that undergo a light
induced chemical reaction when exposed to a wavelength within the
absorption range of the dye to form at least one photoproduct. This
reaction can be a photodecomposition reaction, such as oxidation,
reduction, or bond breaking to form smaller constituents, or a
molecular rearrangement, such as a sigmatropic rearrangement, or
addition reactions including pericyclic cycloadditions. The light
exposure-induced chemical reaction causes a difference in
refractive index in the holographic recording medium between
exposed and unexposed portions of the medium, which allows for
light diffracting interference fringe patterns to be formed when
the medium is exposed to mutually coherent interfering signal and
reference light sources.
[0009] The performance of photoreactive dyes for use in holographic
recording media can be evaluated by a variety of different
criteria, including but not limited to quantum efficiency,
diffraction efficiency, sensitivity, thermal stability, spectral
absorbance, and compatibility with polymer binder(s) used in a
holographic recording/storage medium.
[0010] Quantum efficiency (QE) is a measure of the probability of a
photochemical transition for each absorbed photon of a given
wavelength, and thus is a measure of efficiency with which incident
light is used to achieve photochemical conversion of the dye from
one molecular form to another. Quantum efficiency is given by the
equation
QE = hc / .lamda. .sigma. F 0 ##EQU00001##
where h is Planck's constant, c is the velocity of light, .lamda.
is the wavelength of the light being absorbed, .sigma. is the
absorption cross-section at the wavelength .lamda., and F.sub.0 is
the light fluence. The absorption cross-section is a measurement of
the ability of an atom or molecule to absorb light at a specified
wavelength, and is governed by the Beer-Lambert law for optically
thin samples as shown in the equation
.sigma. = ln ( 10 ) Absorbance N 0 L ( cm 2 ) ##EQU00002##
where N.sub.0 is the concentration in molecules per cm.sup.3 and L
is the sample thickness in cm. Generally, higher QE values are
beneficial for photoreactive dyes in holographic applications, as
they potentially require lower (i.e., shorter and/or lower
intensity) exposures to actinic radiation in order to produce a
photochemically-induced change in the dye compound.
[0011] Diffraction efficiency (DE or i) is a measure of the
difference in refractive index in the holographic recording/storage
medium between exposed and unexposed portions, which is produced by
the photoreactive dye in response to exposure. It is determined
experimentally by measuring the diffracted power of the hologram
and then calculating the diffraction efficiency, .eta., according
to the equation
.eta. = P diffracted P reference ##EQU00003##
where P.sub.diffracted is the diffracted power of the hologram.
[0012] Sensitivity (S) is a measure of the diffraction efficiency
of a hologram recorded using a certain amount of light fluence, F.
Light fluence, F, is determined as the product of light intensity
(I) and exposure time (t). Sensitivity can be represented by the
equation
S = .eta. I t L ( cm / J ) ##EQU00004##
where I is the intensity of the recording beam, t is the recording
time, and L is the thickness of the holographic recording/storage
medium, and .eta. is the diffraction efficiency.
[0013] Various compounds have been proposed as photoreactive dyes
for holographic recording and storage. For example, see US
2006/0073392 A1, US 2009/0081560 A1, and US 2009/0082580 A1.
However, there continues to be a need for new compounds for this
purpose that provide beneficial properties, including but not
limited to any or all of good quantum efficiency, diffraction
efficiency, sensitivity, thermal stability, spectral absorbance,
and/or compatibility with polymer binder(s) used in a holographic
recording/storage medium.
SUMMARY
[0014] Disclosed herein is a holographic recording composition
comprising a polymer binder and a nitrone compound according to the
formula:
##STR00001##
wherein R.sub.1 and R.sub.2 are each independently C.sub.1-C.sub.10
alkyl.
[0015] Disclosed herein too is an article comprising the nitrone
photochromic dye of formula (I) and an organic material, wherein
the article is used as a data storage media.
[0016] Disclosed herein in addition, is a method for recording
information comprising exposing an article that comprises the
nitrone photochromic dye of formula (I) to mutually coherent signal
and reference light sources at a wavelength that causes a change in
the chemical structure of the compound of formula (I).
[0017] Nitrones of formula (I), because of their high decomposition
temperatures are suitable for use in thermoplastic compositions
used in forming (e.g., by injection molding) photoactive components
for holographic applications. Injection molding in holographic
applications improves the processing of such holographic media and
allows the use of polycarbonates and other high T.sub.g (glass
transition temperature) thermoplastic resins.
DETAILED DESCRIPTION
[0018] As noted, holographic data storage relies upon the
introduction of localized variations in the refractive index of the
optically transparent substrate comprising the photoreactive dye as
a means of storing holograms. The refractive index within an
individual volume element of the optically transparent substrate
can be constant throughout the volume element, as in the case of a
volume element that has not been exposed to electromagnetic
radiation, or in the case of a volume element in which the
photoreactive dye has been reacted to the same degree throughout
the volume element. It is believed that most volume elements that
have been exposed to electromagnetic radiation during the
holographic data writing process will contain a complex holographic
pattern, and as such, the refractive index within the volume
element will vary across the volume element. In instances in which
the refractive index within the volume element varies across the
volume element, it is convenient to regard the volume element as
having an "average refractive index" which can be compared to the
refractive index of the corresponding volume element before
irradiation. Thus, in one embodiment an optically readable datum
comprises at least one volume element having a refractive index
that is different from a corresponding volume element of the
optically transparent substrate before irradiation. Data storage is
achieved by locally changing the refractive index of the data
storage medium in a graded fashion (continuous sinusoidal
variations), rather than discrete steps, and then using the induced
changes as diffractive optical elements.
[0019] In one embodiment of the invention, a holographic recording
medium comprising an optically transparent substrate is provided.
The optically transparent substrate can be made of materials
possessing sufficient optical quality such as, low scatter, low
birefringence, and negligible losses at the wavelengths of
interest, to render the data stored in the holographic storage
medium readable. Generally, plastic materials that exhibit these
properties can be used as the substrate. However, the plastic
materials should be capable of withstanding the particular
processing parameters employed (e.g., inclusion of the dye,
exposure to a sensitizing solvent and application of any coating or
subsequent layers, and molding it into a final format) and
subsequent storage conditions.
[0020] Disclosed herein are novel nitrone compounds useful as
photoreactive dyes and optical data storage media, containing the
nitrone compounds, for use in holographic data storage and
retrieval. Also disclosed are methods directed to holographic
storage media preparation, data storage, and data retrieval. The
holographic recording medium is manufactured from a holographic
recording composition that comprises a binder composition and a
photoactive material, wherein the photoactive material comprises a
photochromic dye. The photochromic dye comprises a nitrone compound
of formula (I). The holographic recording media can be
advantageously used for data storage. The holographic recording
media can also be written and read (i.e., data can be stored and
retrieved respectively) using electromagnetic radiation having the
same wavelength.
[0021] The nitrones of formula (I), due to their high decomposition
temperatures, can be processed at temperatures needed for
processing (e.g., molding and extruding) for a variety of
thermoplastics.
[0022] When a particular wavelength light is incident on the
nitrone compound, the nitrone is converted to an oxaziridine.
##STR00002##
[0023] This oxaziridine normally has a different RI compared to the
starting nitrone due to a change in its electronic structure. Thus,
controlled bleaching of these nitrones with light to oxaziridine in
the polymer matrix has the ability to produce structured RI changes
within a polymer matrix. This structured RI change can be
engineered using laser light by the means of holograms to either
write data or create optical elements in polymer matrix.
[0024] As noted above, the photoreactive compound according to the
present invention is a nitrone that can also be referred to as a
photochromic dye. Such photochromic dyes are capable of being
written and read by electromagnetic radiation in a polymeric
material. In one exemplary embodiment, the photochromic dyes can be
written and read using actinic radiation i.e., from about 350 to
about 1,100 nanometers. In a more specific embodiment, the
wavelengths at which writing and reading are accomplished may be
from about 400 nanometers to about 800 nanometers. In one exemplary
embodiment, the reading and writing and is accomplished at a
wavelength of about 400 to about 600 nanometers. In another
exemplary embodiment, the writing and reading are accomplished at a
wavelength of about 400 to about 550 nanometers. In one specific
exemplary embodiment, a holographic medium is adapted for writing
at a wavelength of about 405 nanometers. In such a specific
exemplary embodiment, reading may be conducted at a wavelength of
about 532 nanometers, although viewing of holograms may be
conducted at other wavelengths depending on the viewing and
illumination angles, and the diffraction grating spacing and angle.
Examples of photochromic dyes include diarylethenes,
dinitrostilbenes and nitrones.
[0025] The nitrones described herein can be optionally used in
combination with other photochromic dyes. For example,
diarylethenes that can be used as photoactive materials include
diarylperfluorocyclopentenes, diarylmaleic anhydrides,
diarylmaleimides, or a combination comprising at least one of the
foregoing diarylethenes. The diarylethenes are present as open-ring
or closed-ring isomers. In general, the open ring isomers of
diarylethenes have absorption bands at shorter wavelengths. Upon
irradiation with ultraviolet light, new absorption bands appear at
longer wavelengths, which are ascribed to the closed-ring isomers.
The nitrones described herein can also be used in combination with
other nitrones such as .alpha.-(4-ethylamidophenyl)-N-phenylnitrone
or 2,5-thiophene-bis-2-ethylhexylesterphenyl dinitrone, as well as
others known in the art.
[0026] The nitrones are of generic structure (I):
##STR00003##
wherein R.sub.1 and R.sub.2 are each independently C.sub.1-C.sub.10
alkyl.
[0027] In a more specific exemplary embodiment, R.sub.1 and R.sub.2
are each independently C.sub.1-C.sub.8 alkyl, more specifically
C.sub.1-C.sub.6 alkyl, and even more specifically
C.sub.1-C.sub.4.alkyl In a further exemplary embodiment, R.sub.1
and R.sub.2 are each independently methyl or ethyl, and in a
further more specific exemplary embodiment, R.sub.1 is methyl and
R.sub.2 is ethyl. In an exemplary embodiment, the R.sub.1 and
R.sub.2 alkyl groups are unsubstituted. In another exemplary
embodiment, the R.sub.1 and R.sub.2 alkyl groups are substituted
with known substituent groups such as hydroxyl, halogen, etc.
[0028] Exemplary compounds according to formula (I) include, but
are not limited to
.alpha.-(4-methoxycarbonylphenyl)-N-(4-ethoxycarbononylphenyl)nitrone,
.alpha.-(4-ethoxycarbonylphenyl)-N-(4-ethoxycarbononylphenyl)nitrone,
.alpha.-(4-butoxycarbonylphenyl)-N-(4-ethoxycarbononylphenyl)nitrone,
.alpha.-(4-propoxycarbonylphenyl)-N-(4-pentoxycarbononylphenyl)nitrone,
.alpha.-(4-hexoxycarbonylphenyl)-N-(4-butoxycarbononylphenyl)nitrone,
.alpha.-(4-octoxycarbonylphenyl)-N-(4-octoxycarbononylphenyl)nitrone,
and .alpha.-(4-hexoxycarbonylphenyl)-N-(4-decoxycarbononylphenyl)
nitrone,
.alpha.-(4-methoxycarbonylphenyl)-N-(4-methoxycarbononylphenyl)nitrone,
.alpha.-(4-ethoxycarbonylphenyl)-N-(4-methoxycarbononylphenyl)nitrone,
and others as can be readily envisioned from variations within the
scope of formula (I).
[0029] An exemplary preparation of nitrones can include the
following steps. The first step is the preparation of a
hydroxylamine, as follows:
##STR00004##
where R.sub.1=alkyl ester
[0030] Other methods are known for the preparation of hydroxylamine
from a nitro compound. For example, in one method, an aromatic or
aliphatic nitro compound is converted into a corresponding
hydroxylamine using zinc and ammonium chloride in aqueous alcohol
and then reacted with an aromatic or thiophene dicarboxaldehye. In
another method (a hydrogenation method), nitro compounds can be
converted to their hydroxylamine derivative using hydrogen and Pd/C
or Pt/C in the presence of DMSO.
[0031] The next step is condensation of the hydroxylamine
derivative with an aldehyde employing the following reaction.
##STR00005##
[0032] Upon exposure to electromagnetic radiation, nitrones of
formula (I) undergo unimolecular cyclization to an oxaziridine of
formula (IA):
##STR00006##
wherein R.sub.1 and R.sub.2 have the same meaning as denoted above
for (I).
[0033] Thus, one aspect of the invention relates to an article or
photoproduct that comprises an oxaziridine compound. In some
embodiments, the photocyclization of the photoreactive nitrone dye
to an oxaziridine photoproduct proceeds with a high quantum
efficiency, and a large refractive index change. Typically, the
photocyclization is induced in only a portion of the total amount
of the photoreactive nitrone dye present in a given volume element,
thus providing a refractive index contrast between the unconverted
dye and the oxaziridine photo-product, and providing the
concentration variations of the photo-product corresponding to the
holographic interference pattern, and constituting the optically
readable datum.
[0034] The binder composition can include inorganic material(s),
organic material(s), or a combination of inorganic material(s) with
organic material(s). The binder should be an optically transparent
material, e.g., a material that will not interfere with the reading
or writing of the hologram. As used herein, the term "optically
transparent" means that an article (e.g., layer) or a material
capable of transmitting a substantial portion of incident light,
wherein a substantial portion can be greater than or equal to 70%
of the incident light. The optical transparency of the layer may
depend on the material and the thickness of the layer. The
optically transparent holographic layer may also be referred to as
a holographic layer.
[0035] Exemplary organic materials include optically transparent
organic polymer(s) that are elastically deformable. In one
embodiment, the binder composition comprises elastomeric
material(s) (e.g., those which provide compressibility to the
holographic medium). Exemplary elastomeric materials include those
derived from olefins, monovinyl aromatic monomers, acrylic and
methacrylic acids and their ester derivatives, as well as
conjugated dienes. The polymers formed from conjugated dienes can
be fully or partially hydrogenated. The elastomeric materials can
be in the form of homopolymers or copolymers, including random,
block, radial block, graft, and core-shell copolymers. Combinations
of elastomeric materials can be used.
[0036] Possible elastomeric materials include thermoplastic
elastomeric polyesters (commonly known as TPE) include
polyetheresters such as poly(alkylene terephthalates) (particularly
poly[ethylene terephthalate] and poly[butylene terephthalate]),
e.g., containing soft-block segments of poly(alkylene oxide),
particularly segments of poly(ethylene oxide) and poly(butylene
oxide); and polyesteramides such as those synthesized by the
condensation of an aromatic diisocyanate with dicarboxylic acids
and a carboxylic acid-terminated polyester or polyether prepolymer.
One example of an elastomeric material is a modified graft
copolymer comprising (i) an elastomeric (i.e., rubbery) polymer
substrate having a glass transition temperature (Tg) less than
10.degree. C., more specifically less than -10.degree. C., or more
specifically -200.degree. to -80.degree. C., and (ii) a rigid
polymeric superstrate grafted to the elastomeric polymer substrate.
Exemplary materials for use as the elastomeric phase include, for
example, conjugated diene rubbers, for example polybutadiene and
polyisoprene; copolymers of a conjugated diene with less than 50 wt
% of a copolymerizable monomer, for example a monovinylic compound
such as styrene, acrylonitrile, n-butyl acrylate, or ethyl
acrylate; olefin rubbers such as ethylene propylene copolymers
(EPR) or ethylene-propylene-diene monomer rubbers (EPDM);
ethylene-vinyl acetate rubbers; silicone rubbers; elastomeric
C.sub.1-8 alkyl(meth)acrylates; elastomeric copolymers of C.sub.1-8
alkyl (meth)acrylates with butadiene and/or styrene; or
combinations comprising at least one of the foregoing elastomers.
Exemplary materials for use as the rigid phase include, for
example, monovinyl aromatic monomers such as styrene and
alpha-methyl styrene, and monovinylic monomers such as
acrylonitrile, acrylic acid, methacrylic acid, and the
C.sub.1-C.sub.6 esters of acrylic acid and methacrylic acid,
specifically methyl methacrylate. As used herein, the term
"(meth)acrylate" encompasses both acrylate and methacrylate
groups.
[0037] Specific exemplary elastomer-modified graft copolymers
include those formed from styrene-butadiene-styrene (SBS),
styrene-butadiene rubber (SBR), styrene-ethylene-butadiene-styrene
(SEBS), ABS (acrylonitrile-butadiene-styrene),
acrylonitrile-ethylene-propylene-diene-styrene (AES),
styrene-isoprene-styrene (SIS), methyl
methacrylate-butadiene-styrene (MB S), and styrene-acrylonitrile
(SAN).
[0038] Exemplary organic materials that can also be employed as the
binder composition are optically transparent organic polymers. The
organic polymer can be thermoplastic polymer(s), thermosetting
polymer(s), or a combination comprising at least one of the
foregoing polymers. The organic polymers can be oligomers,
polymers, dendrimers, ionomers, copolymers such as for example,
block copolymers, random copolymers, graft copolymers, star block
copolymers; or the like, or a combination comprising at least one
of the foregoing polymers. Exemplary thermoplastic organic polymers
that can be used in the binder composition include, without
limitation, polyacrylates, polymethacrylates, polyesters (e.g.,
cycloaliphatic polyesters, resorcinol arylate polyester, and so
forth), polyolefins, polycarbonates, polystyrenes, polyamideimides,
polyarylates, polyarylsulfones, polyethersulfones, polyphenylene
sulfides, polysulfones, polyimides, polyetherimides,
polyetherketones, polyether etherketones, polyether ketone ketones,
polysiloxanes, polyurethanes, polyethers, polyether amides,
polyether esters, or the like, or a combination comprising at least
one of the foregoing thermoplastic polymers (either in admixture or
co- or graft-polymerized), such as polycarbonate and polyester.
[0039] Exemplary polymeric binders are described herein as
"transparent". Of course, this does not mean that the polymeric
binder does not absorb any light of any wavelength. Exemplary
polymeric binders need only be reasonably transparent in
wavelengths for exposure and viewing of a holographic image so as
to not unduly interfere with the formation and viewing of the
image. In an exemplary embodiment, the polymer binder has an
absorbance in the relevant wavelength ranges of less than 0.2. In
another exemplary embodiment, the polymer binder has an absorbance
in the relevant wavelength ranges of less than 0.1. In yet another
exemplary embodiment, the polymer binder has an absorbance in the
relevant wavelength ranges of less than 0.01. Organic polymers that
are not transparent to electromagnetic radiation can also be used
in the binder composition if they can be modified to become
transparent. For example, polyolefins are not normally optically
transparent because of the presence of large crystallites and/or
spherulites. However, by copolymerizing polyolefins, they can be
segregated into nanometer-sized domains that cause the copolymer to
be optically transparent.
[0040] In one embodiment, the organic polymer and photochromic dye
can be chemically attached. The photochromic dye can be attached to
the backbone of the polymer. In another embodiment, the
photochromic dye can be attached to the polymer backbone as a
substituent. The chemical attachment can include covalent bonding,
ionic bonding, or the like.
[0041] Examples of cycloaliphatic polyesters for use in the binder
composition are those that are characterized by optical
transparency, improved weatherability and low water absorption. It
is also generally desirable that the cycloaliphatic polyesters have
good melt compatibility with the polycarbonate resins since the
polyesters can be mixed with the polycarbonate resins for use in
the binder composition. Cycloaliphatic polyesters are generally
prepared by reaction of a diol (e.g., straight chain or branched
alkane diols, and those containing from 2 to 12 carbon atoms) with
a dibasic acid or an acid derivative.
[0042] Examples of polycarbonates for use in the binder composition
are those that are characterized by optical transparency, thermal
stability, and good impact strength and other beneficial physical
properties. Polycarbonates are generally prepared by reaction of a
diol (e.g., aromatic diols like biphenol, bisphenol A, and others
well-known in the art) in the presence of an appropriate catalyst,
with a carbonate precursor such as phosgene (interfacial
polymerization) or with a carbonate source such as diphenyl
carbonate (melt polymerization).
[0043] Polyarylates that can be used in the binder composition
refer to polyesters of aromatic dicarboxylic acids and bisphenols.
Polyarylate copolymers include carbonate linkages in addition to
the aryl ester linkages, known as polyester-carbonates. These aryl
esters may be used alone or in combination with each other or more
particularly in combination with bisphenol polycarbonates. These
organic polymers can be prepared, for example, in solution or by
melt polymerization from aromatic dicarboxylic acids or their ester
forming derivatives and bisphenols and their derivatives.
[0044] Blends of organic polymers may also be used as the binder
composition for the holographic devices. Specifically, organic
polymer blends can include polycarbonate
(PC)-poly(1,4-cyclohexane-dimethanol-1,4-cyclohexanedicarboxylate)
(PCCD), PC-poly(cyclohexanedimethanol-co-ethylene terephthalate)
(PETG), PC-polyethylene terephthalate (PET), PC-polybutylene
terephthalate (PBT), PC-polymethylmethacrylate (PMMA),
PC-PCCD-PETG, resorcinol aryl polyester-PCCD, resorcinol aryl
polyester-PETG, PC-resorcinol aryl polyester, resorcinol aryl
polyester-polymethylmethacrylate (PMMA), resorcinol aryl
polyester-PCCD-PETG, or the like, or a combination comprising at
least one of the foregoing.
[0045] Binary blends, ternary blends and blends having more than
three resins may also be used in the polymeric alloys. When a
binary blend or ternary blend is used in the polymeric alloy, one
of the polymeric resins in the alloy may comprise about 1 to about
99 weight percent (wt %) based on the total weight of the
composition. Within this range, it is generally desirable to have
the one of the polymeric resins in an amount greater than or equal
to about 20, preferably greater than or equal to about 30 and more
preferably greater than or equal to about 40 wt %, based on the
total weight of the composition. Also desirable within this range,
is an amount of less than or equal to about 90, preferably less
than or equal to about 80 and more preferably less than or equal to
about 60 wt % based on the total weight of the composition. When
ternary blends of blends having more than three polymeric resins
are used, the various polymeric resins may be present in any
desirable weight ratio.
[0046] Exemplary thermosetting polymers that may be used in the
binder composition include, without limitation, polysiloxanes,
phenolics, polyurethanes, epoxies, polyesters, polyamides,
polyacrylates, polymethacrylates, or the like, or a combination
comprising at least one of the foregoing thermosetting polymers. In
one embodiment, the organic material can be a precursor to a
thermosetting polymer.
[0047] In addition to binder, the optically transparent substrate
can comprise additional components such as heat stabilizers;
antioxidants; light stabilizers; plasticizers; antistatic agents;
mold releasing agents; additional resins; binders, blowing agents;
and the like, as well as combinations of the foregoing
additives.
[0048] In one embodiment, as noted above, in a method for storing
holographic data, an optically transparent substrate containing the
nitrone photochromic dye is irradiated with a holographic
interference pattern, wherein the pattern has a first wavelength
and an intensity both sufficient to convert, within a volume
element of the substrate, at least some of the photoreactive dye
into a photo-product, and producing within the irradiated volume
element concentration variations of the photoproduct corresponding
to the holographic interference pattern, thereby producing an
optically readable datum corresponding to the volume element. The
optically readable datum is stored in the optically transparent
substrate as a hologram patterned within at least one volume
element of the optically transparent substrate.
[0049] Those skilled in the art will appreciate that the lingering
photosensitivity of an unconverted (residual) photochemically
reactive dye can present a problem that can adversely affect the
integrity of the stored data if no step is taken to stabilize the
unconverted photochemically reactive dye. In the case where the
unconverted photochemically reactive dye is a nitrone, protonation
of the nitrone remaining following the recording of the holographic
data can provide an efficient means of preventing further
conversion of the nitrone to photoproducts under the influence of,
for example, a read beam or ambient light.
[0050] In one embodiment, the optically transparent substrate
containing the nitrone photochromic dye is irradiated with a
holographic interference pattern having a first wavelength to
record data. The optically transparent substrate is then irradiated
with radiation having a second wavelength to stabilize the written
data, and the stabilized data can then be read using radiation
having a third wavelength (e.g., a "read beam"), wherein the
radiation at each step can independently have a wavelength from
about 300 nm to about 1,500 nm. In an embodiment, the first,
second, and third wavelengths can be independently between about
300 nm and about 800 nm. In one embodiment, the first wavelength
(or the writing wavelength) for writing and recording the data onto
the holographic data storage medium is from about 375 nm to about
450 nm. In another embodiment, the first wavelength can be from
about 450 nm to about 550 nm. In one embodiment, the first
wavelength is in a range from about 375 nm to about 450 nm and the
second wavelength is in a range from about 450 to about 1500 nm. In
another embodiment, the first wavelength is in a range from about
450 nm to about 550 nm and the second wavelength is in a range from
about 550 to about 1500 nm. In still another embodiment, the
writing wavelength is such that it is shifted by 0 nm to about 400
nm from the wavelength at which the recorded data is stabilized by
the action of light of the second wavelength. Exemplary wavelengths
at which writing and data stabilization are accomplished are about
405 nanometers (writing) and about 532 nanometers (stabilization).
The first wavelength is also sometimes referred to as the "write"
wavelength.
[0051] In one embodiment, the photochromic dye after being reacted
can be converted to a non-photochromic state so that any written
data cannot be destroyed. The conversion of the photochromic dye to
the non-photochromic state can be induced by an electric field, by
a third wavelength, by a photoacid generator or by a combination
comprising at least one of the foregoing.
[0052] In another embodiment of a method of manufacturing the
holographic data storage media, the photoactive material is
disposed upon a first film that comprises an organic polymer. The
first film behaves as a substrate upon which is disposed the
photoactive material. The photoactive material can be disposed upon
the first film in the form of a complete or partial layer. In yet
another embodiment, a second film is disposed upon a surface of the
photoactive material opposed to the surface in contact with the
first film. The first and the second films can be molded or cast
from solution. The second film can be disposed upon the surface of
the photoactive material by molding. The photoactive material is
then coated onto the surface of the first film or the surface of
the second film or upon the opposing surfaces of both the first
film and the second film. Examples of processes by which the
photoactive material can be coated onto the surface of the film are
by brush painting, dip coating, spray painting, spin coating, or
the like.
[0053] When a photochromic material is disposed upon a film to form
the holographic data storage as described above, it is generally
desirable to have the film having a thickness of about 1 to about
100,000 micrometers (.mu.m). In one embodiment, it is desirable to
have a thickness of about 2 to about 10,000 .mu.m. In another
embodiment, it is desirable to have a thickness of about 3 to about
1,000 .mu.m. In yet another embodiment, it is desirable to have a
thickness of about 7 to about 500 .mu.m.
[0054] In another embodiment of a method of manufacturing the
holographic data storage media, the photoactive material can be
incorporated into the organic polymer in a mixing process to form a
data storage composition. Following the mixing process, the data
storage composition can be molded into an article that can be used
as holographic data storage media. Examples of molding can include
injection molding, blow molding, compression molding, vacuum
forming, or the like. The injection molded article can have any
geometry. Examples of suitable geometries are circular discs,
square shaped plates, polygonal shapes, or the like.
[0055] The mixing processes by which the photoactive material can
be incorporated into the organic polymer involves the use of shear
force, extensional force, compressive force, ultrasonic energy,
electromagnetic energy, thermal energy or combinations comprising
at least one of the foregoing forces or forms of energy and is
conducted in equipment wherein the aforementioned forces are
exerted by a single screw, multiple screws, intermeshing
co-rotating or counter rotating screws, non-intermeshing
co-rotating or counter rotating screws, reciprocating screws,
screws with pins, screws with screens, barrels with pins, rolls,
rams, helical rotors, baffles, or combinations comprising at least
one of the foregoing.
[0056] The mixing can be conducted in machines such as a single or
multiple screw extruder, a Buss kneader, a Henschel, a helicone, an
Eirich mixer, a Ross mixer, a Banbury, a roll mill, molding
machines such as injection molding machines, vacuum forming
machines, blow molding machine, or then like, or a combination
comprising at least one of the foregoing machines.
[0057] A holographic composition containing the photochromic
nitrone dye can comprise about 0.1 to about 50 weight percent (wt
%), based on the total weight of the holographic composition. In
one embodiment, the holographic composition comprises about 1 to
about 40 wt %, based upon the total weight of the holographic
composition. In another embodiment, the holographic composition
comprises about 2 to about 20 wt %, based upon the total weight of
the holographic composition. In yet another embodiment, the
holographic composition comprises about 3 to about 10 wt %, based
upon the total weight of the holographic composition.
[0058] In one embodiment, a data storage composition comprising a
photoreactive nitrone and a thermoplastic polymer is injection
molded to form an article that can be used for producing
holographic data storage media. The injection-molded article can
have any geometry. Examples of suitable geometries include circular
discs, square shaped plates, polygonal shapes, or the like. The
thickness of the articles can vary, from being at least 100
micrometers in an embodiment, and at least 250 micrometers in
another embodiment. A thickness of at least 250 micrometers is
useful in producing holographic data storage disks that are
comparable to the thickness of current digital storage discs. In
some embodiments, the thickness can vary from about 100 micrometers
to about 5 centimeters. For example, for use as a DVD or CD storage
device typical thickness is about 600 micrometers to about 1.2
millimeters.
[0059] After the molding of the data storage media the data can be
stored onto the media by irradiating the media with electromagnetic
energy having a first wavelength. The irradiation facilitates the
conversion of the open form of the isomer to the closed form of the
isomer (cyclization) of the photochromic dye thereby creating a
hologram into which the data is encoded.
[0060] The holographic materials as described herein can be exposed
to form holograms using any of a number of exposure setups, which
are well-known in the art. A simple exposure setup, for example, is
described in US 2006/0073392 A1, the disclosure of which is
incorporated herein by reference in its entirety.
Examples of Embodiments
[0061] In one embodiment, a nitrone compound can have the
formula:
##STR00007##
wherein R.sub.1 and R.sub.2 are each independently C.sub.1-C.sub.10
alkyl.
[0062] In another embodiment, a composition can comprise a polymer
and a compound of formula (I), wherein R.sub.1 and R.sub.2 are each
independently C.sub.1-C.sub.10 alkyl.
[0063] In yet another embodiment, a holographic recording
composition can comprise a polymer binder and a compound according
to the formula (I), wherein R.sub.1 and R.sub.2 are each
independently C.sub.1-C.sub.10 alkyl.
[0064] In still another embodiment, a method of manufacturing a
holographic recording medium can comprise mixing a compound
according to formula (I), wherein R.sub.1 and R.sub.2 are each
independently C.sub.1-C.sub.10 alkyl, with a molten thermoplastic
polymer binder to form a mixture, and forming the mixture into a
holographic recording medium.
[0065] In a further embodiment, a method of recording a volume
hologram can comprise exposing a holographic recording medium
comprising a composition that comprises a polymer and a compound
according to formula (I), wherein R.sub.1 and R.sub.2 are each
independently C.sub.1-C.sub.10 alkyl, to mutually coherent signal
and reference light sources at a wavelength that causes a change in
the chemical structure of the compound of formula (I).
[0066] In the various embodiments, (i) R.sub.1 and R.sub.2 in
formula (I) are each independently C.sub.1-C.sub.8 alkyl; and/or
(ii) R.sub.1 and R.sub.2 in formula (I) are each independently
C.sub.1-C.sub.6 alkyl; and/or (iii) R.sub.1 and R.sub.2 in formula
(I) are each independently C.sub.1-C.sub.4 alkyl; and/or (iv)
R.sub.1 and R.sub.2 are each independently methyl or ethyl; and/or
(v) R.sub.1 is methyl and R.sub.2 is ethyl; and/or (vi) the polymer
binder is a thermoplastic polymer, a thermoset polymer, or a
coating; and/or (vii) the polymer binder is a polycarbonate, a
polyestercarbonate or a mixture thereof; and/or (viii) the polymer
binder has a glass transition temperature of at least 120.degree.
C.
[0067] The present disclosure is illustrated by the following
non-limiting examples.
EXAMPLES
Materials:
[0068] Starting Material Ethyl-4-nitrobenzoate, 98% GC pure, CAS
NO. [99-77-4] was procured from Fluka. Methyl 4-formylbenzoate 99%
CAS No (1571-08-0) was from Sigma Aldrich. Basic alumina and
activated carbon was from Loba Chemie.
Synthesis:
[0069] In a first step, the compound
4-carbethoxyphenylhydroxylamine was prepared using the following
reaction:
##STR00008##
[0070] To a 2 litre 3-necked flask, 73.2 g ethyl p-nitrobenzoate,
375 ml ethanol, and 375 ml water were added. To this mixture, 26.8
g Zn and 7.16 g NH.sub.4Cl were added slowly during 30 minutes.
Again to this mixture, 28.6 g Zn and 7.16 g NH.sub.4Cl were added
slowly during 30 minutes. Yet again to this mixture, 28.6 g Zn and
7.16 g NH.sub.4Cl were added slowly during 30 minutes. Stirring was
further continued for 30 minutes. The reaction mixture was
filtered, and the precipitate cake was washed with methylene
dichloride, followed by separation of the organic methylene
dichloride layer of the wash solvent. The methylene dichloride wash
solvent was then distilled to produce 52 ml (59 g) of an oily
residue of 4-carbethoxyphenylhydroxylamine.
[0071] In a second step,
.alpha.-(4-methoxycarbonylphenyl)-N-(4-ethoxycarbonylphenyl)
nitrone was prepared, as follows, using the following reaction:
##STR00009##
[0072] To a 2.0 liter flask were added 45.0 g methyl 4-formyl
benzoate, 300 ml toluene, 50 ml acetic acid, and 57.6 g of
4-carbethoxyphenylhydroxylamine, and stirred for 10 hours. The
solids were filtered out and washed with 100 ml n-hexane and 100 ml
water and dried to yield 79 g of crude
.alpha.-(4-methoxycarbonylphenyl)-N-(4-ethoxycarbonylphenyl)
nitrone.
[0073] 50 g of crude
.alpha.-(4-methoxycarbonylphenyl)-N-(4-ethoxycarbonylphenyl)
nitrone was dissolved with stirring in 800 ml of methylene
chloride. 5% basic alumina (Loba Chemie) and 5% activated carbon
(Loba Chemie charcoal activated granular) were added to the above
solution and stirred for 30 min at room temperature. The mixture
was filtered until clear liquid was obtained. 650 ml of the clear
filtrate was distilled under normal distillation with stirring, and
the resulting solution was cooled to room temperature and filtered
to produce a first batch of pure
.alpha.-(4-methoxycarbonylphenyl)-N-(4-ethoxy carbonyl phenyl)
nitrone, and a second batch was produced similarly. Finally, the
remaining the remaining methylene chloride was flashed off and the
residue collected to yield a total of 40 g of purified product.
Analytical and Evaluative Methods:
[0074] The nitrone compound of the Example above and a number of
comparative compounds were subjected to analysis and evaluation as
described below.
Absorption Spectrum:
[0075] About 2 mg of the compound was added to 100 ml acetonitrile.
The resultant mixture was stirred for about 2 hours or until
complete dissolution of the dye in the acetonitrile. Spectra were
recorded of each solution on a Cary/Varian 300 UV-vis
spectrophotometer. Spectra were recorded in the range of about 300
nanometers to about 800 nanometers. Solution samples were taken in
a 1 centimeter quartz cuvette and acetonitrile was taken as the
blank solvent to be placed in the reference beam path for the
UV-Vis measurement. The sample was exposed to an UV beam at 390
nanometers for one minute. The UV-Vis spectrum the sample was
measured before and after exposure to UV light. The peak
wavelength, .lamda..sub.max, denotes the wavelength corresponding
to the peak in absorption spectra and the .lamda..sub.cutoff
corresponds to the wavelength with relative absorption of 5 percent
of .lamda..sub.max.
DSC:
[0076] DSC experiments were performed to study the thermal behavior
of nitrones especially for melting and decomposition temperature.
The melting or decomposition temperatures were measured in presence
of nitrogen with a heating rate of 10.degree. C./min using a DSCQ10
(TA) instrument.
Quantum Efficiency:
Preparation of Solvent Cast Samples:
[0077] 1 g of polycarbonate pellets was dissolved in 10 ml of
methylene chloride and stirred for about 2 hours or until the
polycarbonate pellets were completely dissolved in the methylene
chloride. 50 mg of nitrone dye was added to the polymer solution
and stirred for about 2 hours or until the nitrone was completely
dissolved in the methylene chloride and polymer solution. Solvent
cast samples were made by pouring the dye-polycarbonate solution
inside a metal ring (5 cm radius) resting over a glass substrate.
The assembly of the metal ring placed over the glass substrate was
placed over a hot plate maintained at a temperature of about
40.degree. C., and the assembly was covered with an inverted funnel
to allow slow evaporation of the methylene chloride. Dried
dye-doped polycarbonate films were recovered after about 4 hours.
The dye-doped polycarbonate films contained 5 weight percent of the
dye.
Quantum Efficiency Measurement:
[0078] Quantum efficiency was determined by bleaching the dried
solvent cast film using a laser source. The absorption spectrum of
the bleached spot was measured in situ using an Ocean Optics
Spectrometer. The change in absorption at the desired wavelength
was monitored over time during exposure. The absorption data is fit
with a first order exponential fit to determine the time constant
for bleaching. The absorption cross section is a measurement of an
atom or molecule's ability to absorb light at a specified
wavelength, and is measured in square cm/molecule. It is generally
denoted by .sigma.(.lamda.) and is governed by the Beer-Lambert Law
for optically thin samples as shown in equation
.sigma. ( .lamda. ) = ln ( 10 ) Absorbance ( .lamda. ) N 0 L ( cm 2
) . ##EQU00005##
Diffraction Efficiency:
[0079] Diffraction Efficiency is a property of the recorded
hologram and hence, the holograms were recorded to measure
diffraction efficiency. For recording of the hologram at 405 nm,
both the reference beam and the signal beam were incident on the
test sample at oblique angles of 45 degrees. The sample was
positioned on a rotary stage, which was controlled by a computer.
Both the reference and the signal beams had the same optical power
and were polarized in the same direction (parallel to the sample
surface). The beam diameters (1/e2) were 4 mm. A color filter and a
small pinhole were placed in front of the detector to reduce
optical noise from the background light. A fast mechanical shutter
was placed in front of the laser to control the hologram recording
time. In the 405 nm setup, a green 532 nm beam was used to monitor
the dynamics during hologram recording. The recording power for
each beam varied from 1 mW to 100 mW and the recording time varied
from 10 ms to about 5 s. The diffracted power from a recorded
hologram was measured from a Bragg detuning curve by rotating the
sample disc by 0.2 to 0.4 degrees. The reported values are not
corrected for reflections off the sample surface. The power used to
read the holograms was two to three orders of magnitude lower than
the recording power in order to minimize hologram erasure during
readout. The diffraction efficiency of the hologram, .eta., is
calculated by using equation:
.eta. = P diffracted P reference ##EQU00006##
where P.sub.diffracted is the diffracted power of the hologram.
Sensitivity:
[0080] Sensitivity (S) is a measure of the diffraction efficiency
of a hologram recorded using a certain amount of light fluence, F.
Light fluence, F, is determined as the product of light intensity
(I) and exposure time (t). Sensitivity was determined using the
equation
S = .eta. I t L ( cm / J ) ##EQU00007##
where I is the intensity of the recording beam, t is the recording
time, and L is the thickness of the holographic recording/storage
medium, and .eta. is the diffraction efficiency.
Results:
[0081] The characterization data for the nitrone dye of the Example
against 11 comparative nitrone dyes is compiled in the table below
for comparison of optical and processing properties. The nitrone
dye of the Example unexpectedly exhibited good to excellent
performance across all parameters while the comparative dyes lack
in at least one performance parameter.
TABLE-US-00001 TABLE I Abs Abs Cut DSC M Max off T ID Sructure (nm)
(nm) (nm) QE (.degree. C.) C. Ex. 1 ##STR00010## 189 336 405 15 102
C. Ex. 2 ##STR00011## 345 348 419 47 187 C. Ex. 3 ##STR00012## 317
349 426 12 180 C. Ex. 4 ##STR00013## 309 365 428 23 155 C. Ex. 5
##STR00014## 275 360 426 30 155 Ex. 1 ##STR00015## 327 341 407 74
176 C. Ex. 6 ##STR00016## 315 354 423 45 248 C. Ex. 7 ##STR00017##
630 350 405 14 240 C. Ex. 8 ##STR00018## 331 342 400 NA NA C. Ex. 9
##STR00019## 363 430 17 111 C. Ex. 10 ##STR00020## 401 343 405 NA
255 C. Ex. 11 ##STR00021## 935 N/A 405 Optical Performance Solu-
bility DSC (wt. % Sensi- DecompT in Blue Green tivity (.degree. C.)
CH.sub.2Cl.sub.2) DE DE (cm/J) C. Ex. 1 ##STR00022## 250 38 40 3.3
100 C. Ex. 2 ##STR00023## 240 7.5 10 1 860 C. Ex. 3 ##STR00024##
224 4.9 13 7 80 C. Ex. 4 ##STR00025## 229 4 3 7 70 C. Ex. 5
##STR00026## 233 17.3 8 10 76 Ex. 1 ##STR00027## 252 20 46 31 900
C. Ex. 6 ##STR00028## 252 0.1 13 3 500 C. Ex. 7 ##STR00029## 245 3
10 1 192 C. Ex. 8 ##STR00030## 256 6 2 8 C. Ex. 9 ##STR00031## 210
5 7 3 C. Ex. 10 ##STR00032## 263 0.3 9 10% 2.3 C. Ex. 11
##STR00033## 250 30 25 7 700
[0082] The singular forms "a," "an," and "the" include plural
referents unless the context clearly dictates otherwise.
[0083] The endpoints of all ranges directed to the same component
or property are inclusive and independently combinable (e.g.,
ranges of "less than or equal to about 25 wt %, or, more
specifically, about 5 wt % to about 20 wt %," is inclusive of the
endpoints and all intermediate values of the ranges of "about 5 wt
% to about 25 wt %," etc.).
[0084] The suffix "(s)" as used herein is intended to include both
the singular and the plural of the term that it modifies, thereby
including at least one of that term (e.g., the colorant(s) includes
at least one colorants).
[0085] "Optional" or "optionally" means that the subsequently
described event or circumstance can or can not occur, and that the
description includes instances where the event occurs and instances
where it does not.
[0086] Unless specifically defined otherwise, technical and
scientific terms used herein have the same meaning as is commonly
understood by one of skill in the art to which this invention
belongs. Compounds are described using standard nomenclature. For
example, any position not substituted by any indicated group is
understood to have its valency filled by a bond as indicated, or a
hydrogen atom. A dash ("-") that is not between two letters or
symbols is used to indicate a point of attachment for a
substituent. For example, --CHO is attached through carbon of the
carbonyl group.
[0087] The term "aromatic radical" refers to an array of atoms
having a valence of at least one and comprising at least one
aromatic group, i.e., a cyclic having 4n+2 "delocalized" electrons
where "n" is an integer equal to 1 or greater. Aromatic radicals
can include heteroatoms such as nitrogen, sulfur, selenium,
silicon, and oxygen, or can be composed exclusively of carbon and
hydrogen. The term "a C.sub.3-C.sub.10 aromatic radical" includes
aromatic radicals having at least three but no more than 10 carbon
atoms. The aromatic radical 1-imidazolyl (C.sub.3H.sub.2N.sub.2--)
represents a C.sub.3 aromatic radical. Exemplary aromatic radicals
include phenyl, pyridyl, furanyl, thienyl, naphthyl, phenylene, and
biphenyl radicals. The aromatic radicals as that term is defined
herein includes unsubstituted and substituted aromatic groups, and
thus also include nonaromatic components. For example, a benzyl
group is an aromatic radical, which comprises a phenyl ring (the
aromatic group) and a methylene group (the nonaromatic component).
The benzyl radical (C.sub.7H.sub.7--) represents a C.sub.7 aromatic
radical. Similarly a tetrahydronaphthyl radical is an aromatic
radical comprising an aromatic group (C.sub.6H.sub.3) fused to a
nonaromatic component --(CH.sub.2).sub.4--. Substituents for the
aromatic radicals include halogens, alkyl groups, alkenyl groups,
alkynyl groups, haloalkyl groups, haloaromatic groups, conjugated
dienyl groups, alcohol groups, ether groups, aldehyde groups,
ketone groups, carboxylic acid groups, acyl groups (for example
carboxylic acid derivatives such as esters and amides), amine
groups, nitro groups, and the like. Exemplary substituted aromatic
radicals include halogenated aromatic radicals such as
4-trifluoromethylphenyl,
hexafluoroisopropylidenebis(4-phen-1-yloxy)
(--OPhC(CF.sub.3).sub.2PhO--), 4-chloromethylphen-1-yl,
3-trifluorovinyl-2-thienyl, 3-trichloromethylphen-1-yl
(3-CCl.sub.3Ph-), 4-(3-bromoprop-1-yl)phen-1-yl
(4-BrCH.sub.2CH.sub.2CH.sub.2Ph-), and the like; and
4-allyloxyphen-1-oxy, 4-aminophen-1-yl (4-H.sub.2NPh-),
3-aminocarbonylphen-1-yl (NH.sub.2COPh-), 4-benzoylphen-1-yl,
dicyanomethylidenebis(4-phen-1-yloxy) (--OPhC(CN).sub.2PhO--),
3-methylphen-1-yl, methylenebis(4-phen-1-yloxy)
(--OPhCH.sub.2PhO--), 2-ethylphen-1-yl, phenylethenyl,
3-formyl-2-thienyl, 2-hexyl-5-furanyl,
hexamethylene-1,6-bis(4-phen-1-yloxy) (--OPh(CH.sub.2).sub.6PhO--),
4-hydroxymethylphen-1-yl (4-HOCH.sub.2Ph-),
4-mercaptomethylphen-1-yl (4-HSCH.sub.2Ph-), 4-methylthiophen-1-yl
(4-CH.sub.3SPh-), 3-methoxyphen-1-yl, 2-methoxycarbonylphen-1-yloxy
(methyl salicyl), 2-nitromethylphen-1-yl (2-NO.sub.2CH.sub.2Ph),
3-trimethylsilylphen-1-yl, 4-t-butyldimethylsilylphen-1-yl,
4-vinylphen-1-yl, vinylidenebis(phenyl), and the like.
[0088] The term "cycloaliphatic radical" refers to a radical having
a valence of at least one, and comprising an array of atoms that is
cyclic but not aromatic. As defined herein, cycloaliphatic radicals
do not contain an aromatic group, but can include one or more
noncyclic components. For example, a cyclohexylmethyl group
(C.sub.6H.sub.11CH.sub.2--) is a cycloaliphatic radical that
includes a cyclohexyl ring (the array of atoms which is cyclic but
which is not aromatic) and a methylene group (the noncyclic
component). The cycloaliphatic radicals can include heteroatoms
such as nitrogen, sulfur, selenium, silicon and oxygen, or can be
composed exclusively of carbon and hydrogen. The term "a
C.sub.3-C.sub.10 cycloaliphatic radical" includes cycloaliphatic
radicals having at least three but no more than 10 carbon atoms.
The cycloaliphatic radical 2-tetrahydrofuranyl (C.sub.4H.sub.7O--)
represents a C.sub.4 cycloaliphatic radical. The cyclohexylmethyl
radical (C.sub.6H.sub.11CH.sub.2--) represents a C.sub.7
cycloaliphatic radical. The aromatic radicals as that term is
defined herein includes unsubstituted and substituted
cycloaliphatic groups. Substituents include halogen groups, alkyl
groups, alkenyl groups, alkynyl groups, haloalkyl groups,
conjugated dienyl groups, alcohol groups, ether groups, aldehyde
groups, ketone groups, carboxylic acid groups, acyl groups (for
example carboxylic acid derivatives such as esters and amides),
amine groups, nitro groups, and the like. Exemplary cycloaliphatic
radicals include those comprising one or more halogen atoms, such
as 2-trifluoromethylcyclohex-1-yl,
4-bromodifluoromethylcyclooct-1-yl,
2-chlorodifluoromethylcyclohex-1-yl,
hexafluoroisopropylidene-2,2-bis(cyclohex-4-yl)
(--C.sub.6H.sub.10C(CF.sub.3).sub.2C.sub.6H.sub.10--),
2-chloromethylcyclohex-1-yl, 3-difluoromethylenecyclohex-1-yl,
4-trichloromethylcyclohex-1-yloxy,
4-bromodichloromethylcyclohex-1-ylthio, 2-bromoethylcyclopent-1-yl,
2-bromopropylcyclohex-1-yloxy
(CH.sub.3CHBrCH.sub.2C.sub.6H.sub.10--), and the like; and
cycloaliphatic radicals include 4-allyloxycyclohex-1-yl,
4-aminocyclohex-1-yl (H.sub.2C.sub.6H.sub.10--),
4-aminocarbonylcyclopent-1-yl (NH.sub.2COC.sub.5H.sub.8--),
4-acetyloxycyclohex-1-yl,
2,2-dicyanoisopropylidenebis(cyclohex-4-yloxy)
(.about.OC.sub.6H.sub.10C(CN).sub.2C.sub.6H.sub.10--),
3-methylcyclohex-1-yl, methylenebis(cyclohex-4-yloxy)
(--OC.sub.6H.sub.10CH.sub.2C.sub.6H.sub.10O--).sub.,
1-ethylcyclobut-1-yl, cyclopropylethenyl,
3-formyl-2-terahydrofuranyl, 2-hexyl-5-tetrahydrofuranyl,
hexamethylene-1,6-bis(cyclohex-4-yloxy)
(--OC.sub.6H.sub.10(CH.sub.2).sub.6C.sub.6H.sub.10O--),
4-hydroxymethylcyclohex-1-yl (4-HOCH.sub.2C.sub.6H.sub.10--).sub.,
4-mercaptomethylcyclohex-1-yl (4-HSCH.sub.2C.sub.6H.sub.10--),
4-methylthiocyclohex-1-yl (4-CH.sub.3SC.sub.6H.sub.10--),
4-methoxycyclohex-1-yl, 2-methoxycarbonylcyclohex-1-yloxy
(2-CH.sub.3OCOC.sub.6H.sub.10O--), 4-nitromethylcyclohex-1-yl
(NO.sub.2CH.sub.2C.sub.6H.sub.10--), 3-trimethylsilylcyclohex-1-yl,
2-t-butyldimethylsilylcyclopent-1-yl,
4-trimethoxysilylethylcyclohex-1-yl
((CH.sub.3O).sub.3SiCH.sub.2CH.sub.2C.sub.6H.sub.10--),
4-vinylcyclohexen-1-yl, vinylidenebis(cyclohexyl), and the
like.
[0089] The term "aliphatic radical" refers to an organic radical
having a valence of at least one, a linear or branched array of
atoms that is not cyclic, and at least one carbon atom. The
aliphatic radicals can include heteroatoms such as nitrogen,
sulfur, silicon, selenium, and oxygen or can be composed
exclusively of carbon and hydrogen. A C.sub.1-C.sub.10 aliphatic
radical contains at least one but no more than 10 carbon atoms. A
methoxy group (--OCH.sub.3) is an example of a C.sub.1 aliphatic
radical. An aliphatic radical, as that term is defined herein,
includes unsubstituted and substituted aliphatic groups.
Substitutents include halogen groups, alkyl groups, alkenyl groups,
alkynyl groups, haloalkyl groups, conjugated dienyl groups, alcohol
groups, ether groups, aldehyde groups, ketone groups, carboxylic
acid groups, acyl groups (for example carboxylic acid derivatives
such as esters and amides), amine groups, nitro groups, and the
like. Exemplary substituted aliphatic radicals include halogenated
aliphatic radicals such as trifluoromethyl, bromodifluoromethyl,
chlorodifluoromethyl, hexafluoroisopropylidene, chloromethyl,
difluorovinylidene, trichloromethyl, bromodichloromethyl,
bromoethyl, 2-bromotrimethylene (--CH.sub.2CHBrCH.sub.2--), and the
like; and allyl, aminocarbonyl (--CONH.sub.2), carbonyl,
2,2-dicyanoisopropylidene (--CH.sub.2C(CN).sub.2CH.sub.2--), methyl
(--CH.sub.3), methylene (--CH.sub.2--), ethyl, ethylene, formyl
(i.e., --CHO), hexyl, hexamethylene, hydroxymethyl (i.e.,
--CH.sub.2OH), mercaptomethyl (--CH.sub.2SH), methylthio
(--SCH.sub.3), methylthiomethyl (--CH.sub.2SCH.sub.3), methoxy,
methoxycarbonyl (CH.sub.3OCO--), nitromethyl (--CH.sub.2NO.sub.2),
thiocarbonyl, trimethylsilyl ((CH.sub.3).sub.3Si--),
t-butyldimethylsilyl, 3-trimethyoxysilylpropyl
((CH.sub.3O).sub.3SiCH.sub.2CH.sub.2CH.sub.2--), vinyl, vinylidene,
and the like.
[0090] "Halogens" include fluorine, chlorine, bromine, and
iodine.
[0091] The term "hydrocarbyl" refers broadly to a substituent
comprising carbon and hydrogen, optional with at least one
heteroatoms, for example, oxygen, nitrogen, halogen, or sulfur;
"alkyl" refers to a straight or branched chain monovalent
hydrocarbon group; "alkylene" refers to a straight or branched
chain divalent hydrocarbon group; "alkylidene" refers to a straight
or branched chain divalent hydrocarbon group, with both valences on
a single common carbon atom; "alkenyl" refers to a straight or
branched chain monovalent hydrocarbon group having at least two
carbons joined by a carbon-carbon double bond; "cycloalkyl" refers
to a non-aromatic monovalent monocyclic or multicylic hydrocarbon
group having at least three carbon atoms, "cycloalkenyl" refers to
a non-aromatic cyclic divalent hydrocarbon group having at least
three carbon atoms, with at least one degree of unsaturation;
"aryl" refers to an aromatic monovalent group containing only
carbon in the aromatic ring or rings; "arylene" refers to an
aromatic divalent group containing only carbon in the aromatic ring
or rings; "alkylaryl" refers to an aryl group that has been
substituted with an alkyl group as defined above, with
4-methylphenyl being an exemplary alkylaryl group; "arylalkyl"
refers to an alkyl group that has been substituted with an aryl
group as defined above, with benzyl being an exemplary arylalkyl
group; "acyl" refers to an alkyl group as defined above with the
indicated number of carbon atoms attached through a carbonyl carbon
bridge (--C(.dbd.O)--); "alkoxy" refers to an alkyl group as
defined above with the indicated number of carbon atoms attached
through an oxygen bridge (--O--); and "aryloxy" refers to an aryl
group as defined above with the indicated number of carbon atoms
attached through an oxygen bridge (--O--).
[0092] Unless otherwise indicated, each of the foregoing groups can
be unsubstituted or substituted, provided that the substitution
does not significantly adversely affect synthesis, stability, or
use of the compound. The term "substituted" as used herein means
that at least one hydrogen on the designated atom or group is
replaced with another group, provided that the designated atom's
normal valence is not exceeded. When the substituent is oxo (i.e.,
.dbd.O), then two hydrogens on the atom are replaced. Combinations
of substituents and/or variables are permissible provided that the
substitutions do not significantly adversely affect synthesis or
use of the compound.
[0093] Exemplary groups that can be present on a "substituted"
position include, but are not limited to, halogen; cyano; hydroxyl;
nitro; azido; alkanoyl (such as a C.sub.2-C.sub.6 alkanoyl group
such as acyl or the like); carboxamido; alkyl groups (typically
having 1 to about 8 carbon atoms, or 1 to about 6 carbon atoms);
cycloalkyl groups, alkenyl and alkynyl groups (including groups
having at least one unsaturated linkages and from 2 to about 8, or
2 to about 6 carbon atoms); alkoxy groups having at least one
oxygen linkages and from 1 to about 8, or from 1 to about 6 carbon
atoms; aryloxy such as phenoxy; alkylthio groups including those
having at least one thioether linkages and from 1 to about 8 carbon
atoms, or from 1 to about 6 carbon atoms; alkylsulfinyl groups
including those having at least one sulfinyl linkages and from 1 to
about 8 carbon atoms, or from 1 to about 6 carbon atoms;
alkylsulfonyl groups including those having at least one sulfonyl
linkages and from 1 to about 8 carbon atoms, or from 1 to about 6
carbon atoms; aminoalkyl groups including groups having at least
one N atoms and from 1 to about 8, or from 1 to about 6 carbon
atoms; aryl having 6 or more carbons and at least one rings, (e.g.,
phenyl, biphenyl, naphthyl, or the like, each ring either
substituted or unsubstituted aromatic); arylalkyl having 1 to 3
separate or fused rings and from 6 to about 18 ring carbon atoms,
with benzyl being an exemplary arylalkyl group; or arylalkoxy
having 1 to 3 separate or fused rings and from 6 to about 18 ring
carbon atoms, with benzyloxy being an exemplary arylalkoxy
group.
[0094] The term "optically transparent" as applied to an optically
transparent substrate or an optically transparent plastic material
means that the substrate or plastic material has an absorbance of
less than 1. That is, at least 10 percent of incident light is
transmitted through the material at least one wavelength in a range
between about 300 nanometers and about 1500 nanometers. For
example, when configured as a film having a thickness suitable for
use in holographic data storage said film exhibits an absorbance of
less than 1 at least one wavelength in a range between about 300
nanometers and about 1500 nanometers.
[0095] The terms "photochemically reactive" and "photoreactive"
have the same meaning and are interchangeable.
[0096] The term "volume element" means a three dimensional portion
of a total volume.
[0097] The term "optically readable datum" is a datum that is
stored as a hologram patterned within one or more volume elements
of an optically transparent substrate.
[0098] All cited patents, patent applications, and other references
are incorporated herein by reference in their entirety. However, if
a term in the present application contradicts or conflicts with a
term in the incorporated reference, the term from the present
application takes precedence over the conflicting term from the
incorporated reference.
[0099] While the invention has been described with reference to
exemplary embodiments, it will be understood by those skilled in
the art that various changes can be made and equivalents can be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications can be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention.
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